Promising price? How can you back up your claim about the future price of your coin?

I am sure you know the answer otherwise you can end up in jail like the PlexCoin founder who made the same promise but turned out he couldn't deliver. He was sentenced for jail due to this scam.

https://news.bitcoin.com/canadian-court-sends-perpetrator-of-plexcoin-ico-scam-to-jail/

So how can you deliver the promised prices?